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Hard Python Dictionary Exercise (programming.dev)
submitted 1 month ago by to c/python@programming.dev
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A hard exercise to help build the right mental model for Python data.

The โ€œSolutionโ€ link visualizes execution and reveals whatโ€™s actually happening using ๐—บ๐—ฒ๐—บ๐—ผ๐—ฟ๐˜†_๐—ด๐—ฟ๐—ฎ๐—ฝ๐—ต: https://github.com/bterwijn/memory_graph

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[โ€“] 3 points 1 month ago (1 child)

Not too familiar with the union operator for dicts, but that result was not what I expected.

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  • [โ€“] [S] 1 point 1 month ago* (last edited 1 month ago)

    The dict union operator is similar to that of set, but in addition the right operand overwrites values of keys of the left operand. It's a nice operator once you get used to it.

    Easy to make a mistake with this exercise:

    • first realize b = b | {3: []} makes a shallow copy
    • then realize the shallow copy still references the value of key 2 in a so we can still append to that and change a
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